Radio transmission system



ril 12 192 AP 7 P. s. CARTER RADIO TRANSMISSION SYSTEM Original Filed June 25. 1923 PHILIP 5. CART-ER Patented Apr. 12, 1927.

UNITED STATES 1,623,996 PATENT OFFICE.

PHILIP S. CARTER, OF NEW BRUNSWICK, NEW JERSEY, ASSIGNOR TO RADIO COR- PORATION OF AMERICA, A CORPORATION OF DELAWARE RADIO TRANSMISSION SYSTEM.

Application filed June 25, 1923, Serial No. 647,463. Renewed'February 12, 1925.

This invention relates to a new and improved radio I signaling system and more specifically to improved means for trans ferring radio frequency energy, generated at a power house, to the antenna or energy radiating circuit;

In the past it has been the custom to erect the antenna of a tran :mitting.system as close as possible to the point where theradio frequency power is generated in order to have a minimum power loss between the generator and the antenna,in the interests of efliciency and economy. However, circumstances occasionally arise where local geographical conditions .or considerations of economy renderit desirable to 'makeuse of an antenna which is located at a di:tan ce from the power house. In the past, under such conditions it was not possible to work efliciently, particularly with short waves, since a given length of transmission line with such waves represents a greater electrical di :tance than withlong waves.-

My invention has for ob ects the provision of a transmission line which will supply radio frequency energy from a power house to an antenna located at a considerable distance away, thus making possible the utilization of existing apparatus at a high efliciency where hitherto only a low efiiciency was possible. Another object of the invention is to provide a new and improved system giving directional transmission utilizing separate antenna: fed from a single source through a plurality of transmission lines.

My invention is illustrated in the accom panying drawing, in which a Figure 1 represents a multiple tuned antenna connected to asource of power through a transmission lin of relatively great electrical length.

Figure 2 shows an equivalent method of coupling the transmission line to the antenna. I

Figures 3 and 4 represent different forms of a directional system according to my invention, utilizing a plurality of antennae supplied from a single source by means of transmission lines. V

Figure 5 shows the directional characteristics of the arrangement disclosed in Figures 3 and 4.

My invention, both as to its theoretical principles and its practical application, will best be understood by reference to the specitic-ationin connection with the drawing, but its scope Wlll particularly be pointed out in the appended claims.

Referring to Figure 1, 1 designates a long or multiple tuned antenna grounded at points 6, 7 8 .and 9 through inductance: 2, 3, 4- and 5. A transmission line 10'is coupled by means of coil 11' to'inductance 2 as will be more particularly pointed out later. An inductance 12 connected across said trans-' mission line is coupled to inductance 13 connected' across the terminals of a. source of power 14. For the purpo.:e of example this is shown in the drawing as an alternator, although any other suitable source, such for instance as an arc converter or a vacuum tube oscillator may be' used for supplying "b u n 1 power to the transmiss on line. and antenna. In order to economize 1n the generating and power transmitting apparatus, it is highly desirable that the apparatus should work at unity power factor; that is" to say, that the current and voltage in the transmission line should be in phase. The power a loss (including radiation) in any transmission hne is 1 R where I represents current and It the effective A. C. resistance, including radiation re1istance. When thetransnussion is at unity power factor, losses in the line are a minimum. Such a result may be obtained if the transmission line is made reflectionless or of electrically infinite length.

tiple tuned antenna this condition is ob:

tained when the feed ratio is equal to R no I This result may be t v I have found that in the case of a mulwhere Z is equal to the surge impedance of the transmission line-"/ 6approx and by the uare of the feed ratio should be equal to t e surge impedance of the'l ne.

Referring to Figure 2, an equivalent R equals the antenna resistance, or stated differently, the antenna resistance multiplied. K

method of connecting the transmission line to a multiple tuned antenna is shown. Here, 21 desi nates the antenna grounded at 23, 25, etc. t rough .coils 22, 24, etc. The transmission line 10 is closed through a suitable amount of coil 22 suchthat the effective impedance of this part of coil 22 with its antenna load is equal to the surge impedance of the line.

Referring to Figure 3, ,I have shown a plurality of open antennae '31 and 34 provided with inductances 32 and 35 and grounded at 33 and 36. These antennae are located wave length apart and are energized by means of transmission lines 10 and 10 which are coupled through coupling coils 37, 37 and 13 to a generator (not shown) and through coils 38 and 38' to coils 32 and 35. Obviously, the same adjustment of coupling coils 38 and 38' is made as before. I I

Figure 4 shows an arrangement substantially equivalent to that shown in Figure 3 with the exception that two multiple tuned antennae are used instead of the two open antennae. In this figure 41 and 41-represen1 two multiple tuned antennae grounded at 44, 45 and 44', 45', respectively through induct"- ances 42, 43 and 42, 43'; A generator (not shown) is arranged to feed antenna 41 and energy is supplied to antenna 41 by means of the transmission line 10 coupled to the source by means of coils 13 and 46 and'to antenna coil 42 by coil 47. The coupling between the transmission line and the antenna should be adjusted to give an effective impedance equal to the surge impedance of the line. It will be seenthat this arrangement is somewhat. directional as shown. in Fig. 5.

It is to be noted that mytransmission .line lends itself particularly to directional systems comprising a plurality of antennae, since the proper phase relation of currents in the various antennae can readily be obtained with a maximum efficiency of transmission line..

While I have shown and described the preferred form of my invention I wish it unders'tood that I do not limit myself to the arrangements shown and described. but that modifications and changes may he made within the scope of my invention aswill beevidentto those skilled in the art to which it appertains.

Having described my invention, what I claim is:

1. In a radio signalling system, the combination of an energy radiating circuit, a

source of power for energizing said circuit and a transmission line of electrically infinite length connecting said circuit and said source.

2. In a radio signalling system, the combination of an energy radiating circuit, a source for supplying energy to said circuit and a transmission line connecting said source and said circuit, said transmission line being constructed and arranged so as to be substantially reflectionless.

3. In a radio signalling system, the combination of an antenna constructed and arranged to radiate energy, a source for supplying energy to said antenna and a con ducting line connecting said source and said. antenna, said line being so constructed and arranged as to prevent the formation of standing waves thereon.

4. In a radio signalling system, the combination of an antenna arranged to radiate energy, a source for supplying said antenna with energy to be radiated and means for transferring energy from said source to said antenna, said means being so constructed and arranged that the voltage and current components of the energy travelling thereon are always in phase 5. In a radio signalling system, the combination of an antenna arranged to radiate energy, a source for supplying energy thereto and a transmission line connecting said source and said antenna, the efi'ective' impedance at the antenna end of said transmission line being equal to the surge impedanceof the line.

6. In, a radio signalling system, the combination of a multiple tuned antenna. a source of power for said antenna and a transmission line for connecting said antenna and said source, characterized by the fact that the antenna resistance multiplied by the feed ratio squared is substantially equal to the surge impedance of the line.

7. In a radio signalling system, the conibi nation of a-plurality of antennae. a single source forsupplying energy to all-of said antennae and transmission lines of electrically infinite length for supplying energy from said source to said antennae.

8. In combination, antennae having a single source of. power supply and grounded through inductances, the source of supply energizing that part of the inductance necessary to give an effective load resistance equal to the surge resistance of transmission means connecting the source and the antennae.

PHILIP S. CARTER. 

